1. Field of the Invention
This invention relates to chemical analysis, and more particularly to apparatus and a method for securing slides during bacteriological and hematological gram stain analysis.
2. Description of the Prior Art
The Gram stain is one of the most widely used and important stains in bacteriology. Originally devised by Hans Christian Gram (Denmark, 1884), it permits the differentiation of two groups of organisms; one group called gram-positive, the other gram-negative. With the Gram-staining method, the gram-positive organisms stain purple, whereas gram-negative organisms stain red. The Gram reaction is correlated with certain basic chemical and physiologic properties of bacteria, and their identification is greatly facilitated by its use.
According to Salton, the color differentiation is due to the formation of a crystal violet-iodine complex "trapped" in the organism, probably by a barrier consisting of the dehydrated and mordanted cell wall. In Gram-positive cells, the barrier becomes impenetrable after treatment with mordant and iodine; in gram-negative cells, the barrier is more penetrable and the solvent extracts the iodine--crystal violet complex. The molecular basis of the reaction is not known; however, in addition to aiding in recognition and identification of organisms, the gram-staining properties seem to denote some very fundamental biologic differences between the "gram-positives" and "gram-negatives" (differential susceptibility to various antibiotics, to lysozyme, etc.). Because of the danger of overstaining or overdecolorizing, it is recommended that at least once a day known gram-negative and gram-positive organisms be stained at the same time as the cultures that are being examined. The following gram-staining technique is the present recommended method.
Hucker modification:
1. Fix the slide in the flame and allow to cool PA1 2. Stain with Hucker crystal violet (S-5) 60 sec. PA1 3. Wash with tap water PA1 4. Stain with Gram's iodine (S-9) 1 min. PA1 5. Wash with tap water PA1 6. Decolorize with 95% alcohol until no further violet comes away (20-30 sec.) PA1 7. Wash thoroughly with distilled water PA1 8. Counterstain with 0.25% safranin (S-12) 20 sec. PA1 9. Wash with tap water PA1 10. Dry in air and examine
Thus, it may be seen that present methods require tilting or dipping the glass slide so that it may be washed free of excess staining solution in order to be able to apply the next staining solution without diluting the previous dye. Because of the necessity for frequent handling of the glass slide, the process is cumbersome and awkward, often causing stains (blue, red, purple) of the fingers and thumbs. These stains are inevitably transferred to lab coats and uniforms worn by laboratory personnel.
One prior art device is known which holds microscope slides stationary during routine and special slide staining. This device employs so-called suction cups and has not proven to be satisfactory for a variety of reasons. Slides are difficult to affix to the cups and when once affixed, are subject to both inadvertent releasing or the opposite, inability to be released, leading to lost time and contamination. Also, the rubberized surface of the cups wears poorly as well. Lastly, the device is clumsy to use and, while trying to attach or detach a slide, there is danger that the glass will break and the operator be injured.
There is therefore a need for an apparatus which would be suitable for securing slides or the like work piece to enable a succession of operations to be performed on the work piece without manual interface for contamination.